RESUMEN
A novel metal-doped carbon quantum dot, zinc-chlorine co-doped carbon quantum dots (Zn/Cl-CQDs), has been developed for the fluorescent probe detection of vitamin B2 and the analysis of the correlation properties of this carbon quantum dot and vitamin B2. Stability experiments demonstrate that Zn/Cl-CQDs possess good fluorescence properties under alkaline conditions. However, when vitamin B2 is added into Zn/Cl-CQDs, the fluorescence intensity decreases sharply, indicating that the fluorescence sensor shows rapid and sensitive detection of vitamin B2 under the static quenching. Lastly, the use of Zn/Cl-CQDs in the detection of vitamin B2 tablets and vitamin B2-rich fruits resulted in recovery rates of 98.2% and 100.6%, respectively. Therefore, this method can be well applied to the detection and analysis of vitamin B2, and has great development prospects in the pharmaceutical industry and food monitoring fields.
RESUMEN
The emerging sample pretreatment technique of magnetic solid-phase extraction (MSPE) has drawn the attention of researchers owing to its advantages of less reagent consumption, fast separation/enrichment process, high adsorption capacity, and simple operation. This paper presents a review of synthesis techniques, classification, and analysis procedures for MSPE in the detection of heavy metals in food. Magnetic adsorbents derived from silica, metal oxides, carbon, polymers, etc., are applied for the detection of heavy metals in food. Then, the recent development of the technology of MSPE for the analysis of heavy metal extraction in food is summarized in detail. Finally, the future outlook for the improvement of MSPE is also discussed.
RESUMEN
A method for the determination of chlormequat chloride (CCC) residues in animal derived foods by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The samples were extracted with acetonitrile containing 1% (v/v) acetic acid and defatted with n-hexane, followed by clean-up on a cationic solid phase extraction column. The analytes were separated on a Venusil MP C18(2) column (150 mm×2.1 mm, 3 µm) under a gradient elution program using acetonitrile and 0.1% (v/v) formic acid aqueous solution as the mobile phases. Then, the analytes were detected by tandem mass spectrometry using a positive electrospray ionization (ESI+) source in the multiple reaction monitoring (MRM) mode. Matrix-matched internal standard calibration curves were used for quantitative analysis. The calibration curves showed good linearity in the range of 0.200-500 µg/L for CCC, with correlation coefficients (r2) no less than 0.9993. The limit of quantification (LOQ) of the method was 0.500 µg/kg. The average recoveries of CCC in pork, beef, mutton, chicken, egg, pig kidney, beef liver, sheep kidney, chicken liver and milk matrices at spiked levels of 0.500-500 µg/kg were 93.4%-101%, and the relative standard deviations were 2.3%-8.0%. The method has less matrix interference, with high sensitivity, accuracy and reliability, and it is suitable for the quantitative detection of CCC residues in animal derived foods.